Fact Sheet
Bureau of Arms Control, Verification, and Compliance
April 1, 2013


Key Point: The Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans any nuclear weapon test explosion or any other nuclear explosion.

Organization: The Treaty establishes an organization -- the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) -- to ensure implementation of the Treaty’s provisions, including the provisions for international verification measures. The CTBTO includes a Conference of the States Parties, an Executive Council, and a Technical Secretariat, which operates the International Data Centre.

Structure: The Treaty includes two Annexes, as well as a Protocol in three parts: Part I on the International Monitoring System (IMS) and the International Data Centre (IDC); Part II on On-Site Inspections (OSI); and Part III on Confidence-Building Measures. There are two Protocol Annexes: Annex 1 lists the locations of treaty monitoring assets associated with the IMS and Annex 2 details possible parameters for screening events.

Verification and inspections: The Treaty's verification regime consists of the IMS composed of seismological, radionuclide, hydroacoustic, and infrasound monitoring stations; a consultation and clarification process; on-site inspections; and confidence-building measures. More than 85 percent of the monitoring stations are currently up and running. The Treaty explicitly provides for the use of national technical means, recognizing its importance for the Treaty's verification regime. Requests for on-site inspections must be approved by at least 30 affirmative votes of the Treaty's 51-member Executive Council.

Treaty compliance and sanctions: It is the sovereign right of each State Party to the Treaty to determine if a violation of the basic obligation of the Treaty has occurred. The Treaty provides for collective measures to redress a situation of concern, to ensure compliance (including sanctions), and for the settlement of disputes. If the Conference of the States Parties or the Executive Council determines that a case is of particular gravity, it can bring the issue to the attention of the United Nations.

Amendments: Any State Party to the Treaty may propose an amendment to the Treaty, the Protocol, or the Annexes to the Protocol. Amendments are considered by an Amendment Conference and are adopted by a positive vote of a majority of the States Parties with no State Party casting a negative vote.

Entry into force: The CTBT will enter into force 180 days after the date of deposit of the instruments of ratification by all 44 of the States listed in Annex 2 to the Treaty. These 44 states participated in the negotiation of the CTBT from 1994-1996 and possessed nuclear power or research reactors at the time.

Review: Ten years after entry into force, a Conference of the States Parties will be held to review the operation and effectiveness of the CTBT.

Duration: The CTBT is of unlimited duration. Each State Party has the right to withdraw from the CTBT if it decides that extraordinary events related to its subject matter have jeopardized its supreme national interests.

Depositary: The Secretary-General of the United Nations is the Depositary of this Treaty and receives signatures, instruments of ratification, and instruments of accession.

[This is a mobile copy of Structure of the CTBT]